﻿#region Legal

// Jimmy Zimmerman
// Team Mongoose
//
// END USER LICENSE AGREEMENT
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// between you (either an individual, business entity, currently active identity of an
// individual with Multiple Personality Disorder, octopus overlord, or otherworldly entity),
// and Team Mongoose, for the enclosed, components.
//
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// terms of this EULA.
//
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// patent, portent, and potential rights to these components.  Team Mongoose
// grants you the right to deploy the enclosed components.
//
// If you agree to the terms of this EULA, a license to use these components is granted to you.
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//
// OTHER RIGHTS AND LIMITATONS
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// attempt to find hidden meanings between the lines of this EULA; unless, of course, you should
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#endregion

using System;
using System.Windows.Input;

namespace Roller.Commands
{
    /// <summary>
    /// Concrete implementation of the ICommand interface that is dependent on a provided 
    /// delegate in order to provide exection.
    /// </summary>
    public class DelegateCommand<T> : ICommand
    {
        #region Fields

        private Action<T> executeMethod;
        private Func<T, bool> canExecuteMethod;

        #endregion

        #region Constructors

        /// <summary>
        /// Creates a new instance of the DelegateCommand class
        /// </summary>
        /// <param name="command">A <see cref="Delegate"/> method provided for executino on command execute.</param>
        public DelegateCommand( Action<T> command )
        {
            if ( command == null )
                throw new ArgumentNullException( "command", "command cannot be null" );

            this.executeMethod = command;
        }

        public DelegateCommand( Action<T> command, Func<T, bool> canExecuteMethod )
        {
            if ( command != null )
                throw new ArgumentNullException( "command", "command cannot be null" );
            if ( canExecuteMethod != null )
                throw new ArgumentNullException( "canExecuteMethod", "canExecuteMethod cannot be null" );

            this.executeMethod = command;
            this.canExecuteMethod = canExecuteMethod;
        }

        #endregion

        #region ICommand Members

        /// <summary>
        /// Executes the supplied delegate method provided when the Delegate Command class as created.
        /// </summary>
        /// <param name="parameter">An <see cref="T"/> supplied as a command parameter.</param>
        public void Execute( T parameter )
        {
            if ( this.executeMethod != null )
                this.executeMethod( parameter );
        }

        /// <summary>
        /// Executes the supplied delegate method provided when the Delegate Command class as created.
        /// </summary>
        /// <param name="parameter">An <see cref="object"/> supplied as a command parameter.</param>
        public void Execute( object parameter )
        {
            this.executeMethod( (T) parameter );
        }

        /// <summary>
        /// Identifies the execution state for the current <see cref="Delegate"/> object.
        /// </summary>
        /// <param name="parameter">An <see cref="T"/> supplied as a command parameter.</param>
        /// <returns>A bool value represent the execution state: True = Command can be executed.</returns>
        public bool CanExecute( T parameter )
        {
            return ( ( this.canExecuteMethod == null ) || this.canExecuteMethod.Invoke( parameter ) );
        }

        /// <summary>
        /// Identifies the execution state for the current <see cref="Delegate"/> object.
        /// </summary>
        /// <param name="parameter">An <see cref="T"/> supplied as a command parameter.</param>
        /// <returns>A bool value represent the execution state: True = Command can be executed.</returns>
        public bool CanExecute( object parameter )
        {
            return this.CanExecute( (T) parameter );
        }

        /// <summary>
        /// 
        /// </summary>
        public event EventHandler CanExecuteChanged;

        #endregion
    }
}
